Venturi flowmeter

What is a venturi tube flow meter?

Venturi flowmeter, also known as venturi tube flow meter,

is a commonly used device for measuring the flow of pressurized pipelines.

It is a differential pressure flowmeter,

and is commonly used to measure the flow of air, natural gas, gas, water, and other fluids.

It consists of a “contraction section”, a “throat” and a “diffusion section”,

which are installed on the pipe where the flow rate needs to be measured.

The classic venturi tube is designed and manufactured,

according to China GB/T2624-93,

and is verified according to the verification procedure JJG640-94.

In the standard throttling device,

it requires the shortest upstream and downstream straight pipes,

the lowest pressure loss, stable performance and convenient maintenance.

Because of its accurate calculation and low energy consumption,

it has been widely used in petroleum, chemical, electric power,

and metallurgy industries.

Features of Venturi flow meter

Venturi flowmeter
  • Less head loss than an orifice or nozzle meter, due to the streamlined design
  • Ideal for clear gas, liquid or steam applications
  • Available in many materials and end arrangements
  • Can be equipped with fittings to accept secondary instrumentation packages

The classic venturi tube is simple, durable and stable in performance.

Classic venturi pressure loss is small, saving the energy needed for fluid delivery.

Classic venturi tube in the range of 50 ~ 1200.

No real-flow calibration is required.

Beyond this range, you can refer to the design and manufacture.

When high precision is required, real-time calibration is possible.

The body is installed in long size,

and it is not convenient for transportation and installation for large-diameter instruments.

Venturi flowmeter parameters:

1. Nominal diameter: 50mm≤DN≤1200mm (more than this range needs to be calibrated)                 

Roughcasting shrinkage section: 100mm ≤ DN ≤800mm                

Mechanical processing shrinkage section: 50mm ≤ DN ≤ 250mm                 

Shrinking section of rough welded iron plate: 200mm≤DN≤1200mm

2. Throttle aperture ratio β: 0.3 ≤ β ≤ 0.75                    

Roughcast shrinkage segment: 0.3 ≤ β ≤ 0.75                   

Machining shrinkage section: 0.4 ≤ β ≤ 0.75                    

Coarse section of rough welded iron plate: 0.4≤β≤0.7

3. Reynolds number range: 2 × 10 5 ≤ ReD ≤ 2 × 10 6                  

Rough cast shrinkage section: 2 × 10 5 ≤ ReD ≤ 2 × 10 6                   

Machining shrinkage section: 2 × 10 5 ≤ ReD ≤ 2 × 10 6                   

Shrinkage section of rough welded iron plate: 2×10 5≤ReD≤2×10 6

4. Accuracy level: 1

Classic venturi flowmeter structure

venturi flowmeter structure
venturi flowmeter structure

The axial section of the classic venturi is shown in the figure above.

It is composed of an inlet cylinder section A,

a conical contraction section B,

a cylindrical throat C,

and a conical diffusion section E.

The diameter of the cylinder section A is D, the length is equal to D;

the contraction section B is conical and has an angle of 21 ° ± 1 °;

the throat C is a cylindrical shape of diameter d, the length of which is equal to d;

E is conical and has a diffusion angle of 7° to 15°.

The constricted section of the classic venturi is divided into three forms:

a coarse cast shrinkage section, a machined shrinkage section,

and a coarse welded iron plate shrinkage section.

The upper-pressure port and the throat pressure port of the classic venturi,

are made into several (not less than four) separate tube wall pressure ports,

and several separate tube walls are pressure-connected by a pressure equalizing ring.

When d≥33.3mm, the diameter of the throat pressure port is 4~10mm,

the diameter of the upstream pressure port should be no more than 0.1D;

when d≤33.3mm, the diameter of the throat pressure port is 0.1d~0.13d,

The diameter of the upstream pressure tap is 0.1d to 0.1D.

How does a Venturi meter work?

Venturi flowmeter working principle
Venturi flowmeter working principle

The Venturi flow meter produces a differential pressure,

to calculate flow rate through a pipe.

The meter works by measuring the pressure of fluid before and after it passes through a narrow tube;

the pressure difference indicates the volumetric rate of flow.

The basic measurement principle of the new generation,

of differential pressure flow measuring instruments,

is the flow measurement method based on the law of conservation of energy

– the primary effort equation and the flow continuity equation.

The inner venturi consists of a circular measuring tube,

and a special core placed in the measuring tube and coaxial with the measuring tube.

The outer surface of the special core has a geometric profile,

similar to the inner surface of a classic venturi,

and forms a different diameter annular flow gap with the inner surface of the measuring tube.

The throttling process of the fluid,

flowing through the inner venturi,

is substantially similar to the throttling process of the fluid,

flowing through the classic venturi and the annular orifice.

This structural feature of the inner venturi makes it not have sharp edge erosion,

and fouling of the orifice plate in the process of use,

and can provide a gradient of the fluid velocity distribution in the pipe,

before throttling and various possible.

The non-axisymmetric velocity distribution performs effective flow adjustment (rectification),

enabling high accuracy and high stability flow measurement.

Where is Venturi meter used?

Since its development,

venturi products have been successfully applied to the measurement of high-humidity natural gas,

low-pressure dirty biogas, coke oven gas, gas, steam, hot water, high-temperature hot kerosene, etc.,

and the practical application range is rapidly expanding.

Besides, the venturi tube has a unique measurement advantage,

for measuring conditions such as long straight pipe installation conditions,

special high temperature, high pressure, strong corrosive and dirty media,

and non-single phase flow measurement.

Sino-Instrument, China, supplies all kinds of Flow Meters.

Provide professional flow measurement solutions.

Sino-Instrument offers over 50 flow meter products.

About 50% of these are differential pressure flow meters (like the Orifice flow meter),

40% are Magnetic Flow Meters, and 40% are Thermal mass flowmeters.

A wide variety of Annubar flow meter options are available to you,

such as free samples, paid samples. 

Sino-Instrument is a globally recognized supplier and manufacturer of flow measurement instrumentation,

located in China.

The top supplying country is China (Mainland),

which supply 100% of the turbine flow meter respectively. 

Sino-Instrument sells through a mature distribution network that reaches all 50 states and 30 countries worldwide.

Annubar flow meter products are most popular in Domestic Market, Southeast Asia, and Mid East. 

You can ensure product safety by selecting from certified suppliers,

with ISO9001,ISO14001 certification.

product image
Author Rating
Aggregate Rating
no rating based on 0 votes
Brand Name
Product Name
Venturi flow meter
USD 300
Product Availability
Available in Stock

Leave a Reply

Your email address will not be published. Required fields are marked *